One sunny day in the borough of Brooklyn, a couple of friends are sitting in a coffee shop, talking about a book that had one had recently read -- a dreadful piece of drek (in her opinion) detailing the true story of how the author had spent two years emulating the lifestyle of the lowly cockroach in order to prepare himself for the upcoming Mayan apocalypse.

The disgruntled friend has just grandly exclaimed to her laughing pal something akin to, "It's good that he's studying up to be the last dude on Earth, because that's the only way he'll ever get a date," when the young man across from the duo stands up, spills his coffee all over the table in a state of extreme agitation and cries, "I'm sorry you hated my book so much! And for your information, tons of girls are into entomology!"

In the RL realm, such an instance could be seen as completely serendipitous, and the girl isn't really to be faulted for her less-than-favorable view of the book in question. But transpose this scenario into what is essentially the digital coffee shop of the Web -- Twitter -- and you have another situation altogether.

More and more, Twitter is becoming a kind of online comment box, a place for fans and customers to weigh in with their myriad opinions. Which is good, in many instances. Brands get constructive feedback! Musicians and fans make friends and collaborate! An open dialogue is forged!

Your favorite band, Emo Screamo, has just posted their upcoming tour dates, and your hometown of Pinprick, USA, is unfortunately not on the docket this go-around. Rage and disappointment flood your eyes and a torrent of salty tears cascade onto your keyboard, effectively shorting out the "F" key. Blasting Emo Screamo's number-one hit, "Time of Death: Your Kiss," you take to Twitter, sending off the following waterlogged words into the abyss, "uck you, emo screamo! uck youuuuuuu!"

Emo Screamo's lead singer, Johnny Longbangs, happens to see your tweet and takes it to his black, black heart, shooting back at you in rage, "uck you, too, you illiterate toolbag." At first, the joy at seeing the you-addressed tweet in your timeline blinds you to his rageful words, and then the slow realization that your favorite singer likely hates you fills you to the eartips with anguish.

"I'm sorry, man," you type back rapidly, "I just really wanted to you to play in Pinprick, ya know? I was just disappointed." But it's too late, friend, Longbangs has retreated into his dark cave of sadness, and has vowed to never set foot (or "oot") in Pinprick as long as Emo Screamo is a band (which will be about six more months, tops).

Yeah, that was all a little dramatic, but the main takeaway is: Be specific about your gripe, don't just rage. If you're sad that your favorite band is skipping your burg, tweet a special invite to play your church and crash on your couch; if a journalist gets a fact wrong, tweet a correction, don't call him/her an expletive, expletiving, expletive -- because you never know when the object of your ire will actually take note of your blistering display of inner turmoil.

Be careful how you at-reply

Tweeting directly at a person, brand, etc. is equivalent to running up to him/her/it on the street and yelling, "HEY, HEY, HEY, listen to me. I have something to say to YOU and only YOU!"

When it comes to people, before you hit "@" try to imagine yourself saying your piece to said person's face. Are you looking for a direct reaction from said person? Would you speak your tweet to his/her face? If not, maybe just tweet something a little more general (taking #1 into consideration).

When tweeting at brands, think about your end game: Are you trying to get faster service from Time Warner? Sure, send a (see number one, constructive) tweet to the company. Expressing a blanket distaste for Candy Corn Oreos? Maybe don't personify the snacks by sending a tweet reading, "@Oreo, your new candy-corned flavored spawn was obviously crafted in the bowels of hell." Unless, you know, you want to be openly mocked on Dumb Tweets At Brands. Special exception for the dude who elicted this tweet from Dominos.

Will your job take a hit?

This should be obvious, but if you work in a certain industry, you should probably be careful what you say about that industry in a public sphere such as Twitter. Still, people are getting fired for doing just that, it seems, so we'll just leave this here.

Does the medium fit the message?

Tons of musicians got all up in arms the other week when singer Amanda Palmer put out a call on her blog asking for volunteers to play horns and strings -- for free -- during select gigs on her current tour (after raising more than a million dollars on Kickstarter for her new album).

Yeah, Palmer and Vaillancourt-Sals may still agree to disagree, but at least the latter managed to open up a dialogue with her considered and articulate letter -- a dialogue that would have lost a lot of its cohesion and luster if confined by character limits.